Responsive design

Western warplanes and naval vessels fired a barrage of missiles at three Syrian chemical weapons sites, the opening salvo in what could be a sustained campaign against the government of President Bashar al-Assad and his supporters.

U.S. military officials said the bombardment, a coordinated effort involving both Britain and France, began at 9 p.m. EDT Friday and rained down more than 100 cruise missiles on Syrian facilities in the capital, Damascus, and the city of Homs.

“Right now, this is a one-time shot,” U.S. Defense Secretary Jim Mattis told Pentagon reporters late Friday, cautioning more strikes could be in the works.

“That will depend on Mr. Assad, should he decide to use more chemical weapons in the future,” Mattis said.

The decision to strike, made after consultations between Washington, London and Paris, came after military and intelligence officials concluded the Assad government was indeed responsible for a chemical weapons attack on the town of Douma last Saturday that killed more than 40 people, including women and children, and sickened hundreds more.

​Use of chemical weapons

U.S., British and French officials have expressed a high degree of confidence the attack on Douma by pro-Assad forces used chlorine gas, and that it also likely used another chemical agent, possibly sarin.

Syrian officials have continually denied their forces used chemical weapons. And Russia, which has backed President Assad since before the start of the conflict in Syria, alleged early Friday that the attack was staged by Britain, a charge rejected by both Britain and the United States.

Still, following the strikes, Russia’s ambassador to the U.S. Anatoly Antonov warned the United States, Britain and France would face consequences.

“Our warnings have been left unheard,” Antonov said in a statement posted on Twitter.

“A predesigned scenario is being implemented,” he said. “Insulting the president of Russia is unacceptable and inadmissible.”

WATCH: President Trump Announces Strikes Against Syria

Addressing the American public after ordering the strikes, President Donald Trump said he was compelled to act after witnessing what he described as “the crimes of a monster” in Douma.

“The purpose of our actions tonight is to establish a strong deterrent against the production, spread and use of chemical weapons … a vital national security interest,” Trump said.

“We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents,” he added.

​Russian support for Assad

Despite such confidence, other U.S. officials remained wary, warning before the strikes that while Syria’s use of chemical weapons cannot be tolerated, much more is at stake given the backing the Syrian government gets from Moscow.

“This is a chess game and the Russians are ratcheting up the pressure,” a U.S. official told VOA on the condition of anonymity given the sensitivity of the situation.

“They’re playing dirty,” the official added. “We need to think two or three steps ahead.”

Complicating any U.S. response is the presence of Russian and Iranian forces on the ground in Syria, one official saying it has “grown and matured” since the United States carried out airstrikes again the Syrian government last April after a sarin gas attack on the rebel-held town of Khan Sheikhoun.

​Trump: Russia responsible

In his remarks, Trump said he holds Russia directly responsible for the attack on Douma, saying Moscow failed to live up to its 2013 promise to guarantee Syria eliminated its arsenal of chemical weapons.

“No nation can succeed in the long run by promoting rogue states, brutal tyrants and murderous dictators,” the U.S. president said. “Russia must decide if it will continue down this dark path or if it will join with civilized nations.”

British Prime Minister Theresa May also blamed Russia for thwarting diplomatic efforts to put an end to the use of chemical weapons in Syria.

“There is no practicable alternative to the use of force to degrade and deter the use of chemical weapons,” May said in a statement. “We cannot allow the erosion of the international norm that prevents the use of these weapons.”

Long-term impact of strikes?

While military officials are still assessing the effectiveness of the strikes, there are growing questions about the long-term impact.

“Strategy hasn’t been this administration’s strong suit — Assad and Putin aren’t going to flinch fast and will easily endure military strikes,” Brett Bruen, a former director of global engagement at the White House, told VOA.

“This only works if they can keep up strong diplomatic pressure on Syria, Russia,” he said. “Otherwise, they will worsen our position and the situation on the ground.”

Brian Katulis at the Center for American Progress, is more hopeful.

“This is a very focused strike for one purpose to make sure that countries around the world will not use weapons of mass destruction on a regular basis,” he said. “I think that’s what the president is trying to do and I think he did the right thing.”

U.S. defense officials said Friday they did not consult their Russian counterparts about the strikes, or notify them in advance, though they did use existing lines of communication to de-conflict the airspace to prevent any accidental incidents between U.S. and Russian planes.

​Targeted strikes

Defense officials said the U.S.-led strikes did encounter some initial resistance from Syrian air defense systems, but that it appears Russian defense systems did not engage.

The first target, they said, was a research center involved in the development and production of chemical and biological weapons.

The two other targets, to the west of Homs, Syria, included storage facilities for sarin gas, other chemical weapon precursors and equipment, as well as a key command post.

“We selected these specific targets both based on the significance to the [Syrian] chemical weapons program as well as the location and the layout,” said U.S. Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff. “We did not select those that had a high risk of collateral damage and specifically a high risk of civilian casualties.”

Steve Herman at the White House; Katherine Gypson and Aru Pande in Washington.